Abstract: A mechanical filter includes a pouch with a double-walled envelope housing a shock-absorbing material in the form of a gel displaceable under pressure. The envelope, of selected geometry, is mainly formed of a thin film of synthetic thermoplastic material, whose physical properties are selected to prevent breakage during displacement of the gel.

Abstract: The invention relates to an internal obturator for a pipe for use in separating two spaces inside a pipe. The obturator comprises a rigid hollow body comprising two end plates connected by a cylinder having a lesser diameter than the end plates between which an annular inflatable bladder of a jack is provided extending around the cylinder. The jack is inflated to apply a cylindrical wall against the inner surface of the wall of the pipe. The wall which is independent of the bladder of the jack may be connected by its ends to the end plates or may simply be inserted therebetween.

Abstract: The invention relates to an internal obturator for a pipe, particularly for a hydrocarbon conveying pipe-line, which comprises a central core and a flexible inflatable sleeve surrounding the core, wherein the central core comprises a flexible casing filled with a hardenable material which is hardened after its introduction into the flexible casing. The hardenable material may be hardened before or after insertion of the obturator into a pipe.

Abstract: A soft retaining gripper for gripping a surface while stresses are exerted in a longitudinal direction parallel to the surface between the gripper and the surface, comprises a jaw and an inflatable flexible bladder carried by the jaw, the bladder being in use inflated to grip the surface. To prevent creep of the gripper in use, a wall is associated with the bladder and extends between the bladder and the surface, the wall being made of a composite anisotropic material comprising elongate elements which are oriented to extend in the longitudinal direction and are practically inextensible and a flexible synthetic resin in which the elongate elements are embedded, the elongate elements being anchored to the jaw at at least that end in the direction of which creep might otherwise occur.

Abstract: An inflatable seal comprises a flexible active part and a rigid part which together define a chamber to be pressurized to place the active part in its operative position and to be evacuated to place the active part in its inoperative position, the active part being made from a composite material comprising an elastic material in which a wide deformable mesh of fibers of low extensibility is incorporated such that the active part has anisotropic elasticity and mechanical strength sufficient to withstand the differential pressures extend thereon in its operative and inoperative positions without the need for external reinforcements.